Polymerized hydrocarbon oils



Nov. 3, 1942. E..R.K|RN Erm.

POLYMERIZED HYDROCARBON OILS Filed oct. 8. 19:58

Patented Nov. 3, 1942 l UNITED STATES PATENT. OFFICE rotmmzanzoxlircmou oms Emmet B. Kirn and Nathan Fragen, Hammond,

Ind., asslgnors to Standard Oil Company. Chicago, lll., a corporation of Indiana Application October 8, 1938, Serial No. 233,995

foams. This invention relates to the conversion of hydrocarbon gases into useful oils and particularly lubricating oils and gasoline. One ofthe objects of the invention is to convert the butanebutylene fraction of cracking still gases into high quality lubricating oils and motor fuels. Another object of the invention is to polymerize the -unsaturated constituents of a four carbon atom fraction of said gases by means'of a catalyst, thereby producing a product of 'wide boiling range and thereafter distilling said product into several fractions which are separately handled. Other objects of the invention will be set forth hereinafter.

The invention is illustrated by a drawing which shows diagrammatically a complete layout for carrying out the process.. Referring to the drawing. a liquefied normally gaseous hydrocarbon stream is introduced by line Il into reaction chamber -I I. The hydrocarbon stream may suitably comprise a mixture of butanes and butylenes derived from the fractionation of cracking still gases. As 4an example of such a mixture, we may use one containing about 10 to 20% of isobutyl-` ene, about 20 to 30% of .normal butylenes and the remainder mostly isobutane and normal butane. 'Ihe gases may be washed with caustic soda or other reagent to remove Hrs or other sulfur compounds and with dilute acids to remove I amines they may contain.. Suitable unsaturated C4 hydrocarbon gases may also be obtained from dehydrogenating butanes from natural gases.

In the reactor II, there is also introduced by' line I2 a stream of catalyst-preferably boronA fluoride. However, boron chloride and other catalytically active metal'halides may be employed. The temperature of the reaction mixture in chamber. II maybe controlled by coolingcoil I3, a suitable temperature being between and 100 F., for example, 40 F. In the reaction chamber II, the isobutylene contained in the hydrocarbons is polymerized by the catalyst, the

.reaction requiring about to 30 minutes. The

amount of catalyst may be suitably about 0.1 to

4 2% of the weight of the total hydrocarbons treated, 0.2 to 0.5% being commonly employed. The reaction products are conducted by line receiver 29a.

If desired, a gasoline fraction may also be removed by stripper I1.

The remaining products are conducted by line 2| and pressure reducing valve 22 to fractionator 23 which may be operated under partial vacuum. In fractionator 23, the product is separated into an over-head gas fraction and side fractions comprising gasoline, cycle oil, and a Diesel lubricating oil hereinafter more fully described. A residual heavy oil fraction is withdrawn by line 24 and conducted to depolymerizer 25 x,by pump 26.' This residual heavy oil may be blended with the cycle oil to produce a high quality shock absorber oil if desired.

The gasoline fraction withdrawn by line 21 may be discharged from the system through valve 23 to receiver 21a and employed in the manufacture of high knock-rating gasolines. By proper adjustment of valves in lines 21, 46, 32 and 35, the gasoline fraction may be .recycled to reactor II or it may be depolymerized in depolymerizer 25. A Diesel lubricating oil is withdrawn from the system by line 26 leading to An intermediate fraction termed cycle oil" is withdrawn by line 30 and conducted through valves 3| and 45 by line. 32 to pump 33 which recycles it by line 34 to reactor Il. The

introduction of cycle oil, consisting of hydrocar-4 flcation of the polymerization reaction. If desired, valve 3| may be partially or fully closed and cycle oil may be transferred by line 35 and valve 36 and pump 26 to depolymerlzer 25.

Il towasher I5 in which any excess catalyst or i acid products, e. g., HF or HCl may be neutralized with water or alkali, for example sodium hydroxide. V'I'hence the products are conducted by line I6 to stripper I1 in which the unreacted gases are vaporized and removed by line I3, heat being supplied by coil I9. and reflux by coil 20.

In the depolymerlzer 25, the undesired by-l products of the Diesel lubricating fraction are decomposed either by heat alone or by heating with a suitable catalyst which A"frnay be placed in chamber 31. When heat alone is employed,

we prefer to operate at a temperature of about 600 to 1000" F. In the presence of catalysts, however, we may use temperatures of about 400 to 600 F., depending on the catalyst. Suitable catalysts are, for example, activated bentonite or a catalyst comprised of aluminum oxide adsorbed on silica gel. l

Decomposition of the undesired by-'products results in the formation of unsaturated, hydrocarbons, both liquid and gases. example, are readily produced by the decomposition of corresponding butylene polymers, particularlyfpolymers of isobutylene. 'In addition, some of the heavy hydrocarbons present in the residual Butylenes for oll from fractionator 23 may be partially depolymerized to oils of intermediate viscosity which may subsequently be recovered as Diesel lubricating oils.

The depolymerized products from 25 and 3l are conducted by valved line 38 through cooler 39 and thence by line 39 to reactor li wherein unsaturated constituents, including the butylenes, are repolymerized to oils within the Diesel lubricating oil range together with other polymerization products. If desired, however, valve 40 may be closed and valve 4l opened to direct the depolymerization products by line 42 into fractionator 23. Here the products of depolymerization are subjected to distillation, heavy constituents being recycled to depolymerizer 25 by line 24 and pump 26. Lighter products of depolymerization are fractionated and separated into the desired Diesel lubricating oil which is withdrawn by line 29, cycle oil and gasoline. Gases, including butylenes, are conducted by line 43 and pump 44 to reactor ll wherein they are Aagain subjected to polymerization.

The Diesel lubricating oil withdrawn by line 29 is characterized by unusually lhigh viscosity index, a low pour point, and low volatility, coupled with unusual freedom from sludge formation when subjected to high load conditions existing within Diesel engines. As a result of these properties, this oil, when employed for the lubri.

cation of pistons of Diesel engines, enables these engines to be operated longer periods of time and under high load conditions without seizure 'or scoring of the pistons and cylinder walls which commonly results from carbonization of the pistonrings by ordinary type oils. It is preferred to regulate the fractionation in tower 23 to produce Diesel oil's having a viscosity within the range of about S. A. E. 20 to S. A. E. 50 and gravity of about 32 A. P. I. Theoil is wax free and the pour point is about -30 F. for the oil of viscosity 30 lS. A. E. T he distilled Diesel lubricating oil may have a viscosity index of about 80 to 95 (Dean and Davis scale).

In order to make the heavier grades of Diesel lubricating oil distillates, we prefer to carry out the fractionation in two stages instead of one stage as illustrated by tower 23. By employing another stage of distillation, we prefer to conduct the fractionation in 23 at atmospheric pressure, removing gasoline and perhaps cycle oil. The remaining products, including the desired Diesel lubricating oil, may be conducted by line taken off at about 485 to 520 F., the temperature at the bottom of the vacuum tower being about 565 to 590 F. The distillate was a typical Diesel lubricating oil of 30 S. A. E. grade. The Saybolt viscosity was between500 and 625 sec. at 100 F. and the gravity, 31.6 to 32.7 A. P. I. Varia.- tions are due largely to the difference in feed stocks and variations in the polymerization reacl tion conditions.

One f thel outstanding characteristics of our invention is the flexibility in operation obtained in the process, depending on the character and the 'amount of the products desired. Thus, the distillation in fractionator 23 may be regulated -fy theV reaction in polymerizer Il.

to produce Diesel lubricating oil of a wide range of viscosities, for example, 20, 30, 40 or 50 S, A. E. viscosity. Likewise, the conditions of polymerization in reactor ii may be varied tc alter the character of the polymerization products. It is preferred to conduct the polymerization in reactor Ii at temperatures within the range of O to F., the preferred temperature` being about 40 to 60 F. Higher temperatures encourage the formation of vlighter polymers, thus increasing the yield of gasoline, cycle oil and light Diesel lubricating oil. Likewise, the recycling of undesired polymerization products and depolymerized products may be varied as described to mod- Thus, recycling the depolymerized products by line 42 to fractionator 23 results in an increase of the isobutylene and light olefin concentration in Il by introduction of these light products through line 43. On the other hand, recycling polymerization products by lines 32 and 34 decreases the concentration of light or normally gaseous olens in polymerizer ll. The reaction in Il is accordingly modified, resulting in the formation of polymerization products of lower average molecular weight.

It should be understood that the gasoline, cycle i oil, and Diesel lubricating oil fractions withdrawn from the fractionator 23 by lines 21, 30,` and 29, respectively, may be subjected to stripping in the customary manner in order to remove undesirable low boiling constituents from each product. The gasoline fraction collected in receiver 21a may have a knock-rating of about '75 to 90 octane number (C. F. R. motor method) fand it may be subjected to suitable hydrogenation to remove olefin constituents when employed for aviation engine fuel.

In carrying out the depolymerization in 25, the time of heating may be varied from a few seconds to several minutes. For example, with a contact time of 10 to 100 seconds and a temperature of 929 F. at atmospheric pressure, the product contained 20 to 30% of C4 fraction, largely isobutylene. If the polymer oil, particularly the lighter cycle oil, is heated for a longer time, lower temperatures may be used; Thus, at 600 to 610 F., 21% decomposition occurred in 23 minutes.

Although we have described our process with respect to certain embodiments thereof, we intend that it be limited only by the following claims.

We claim:

1. In the process of converting normally gaseous olefin hydrocarbons into distillate lubricating oil, the method of increasing the yield of said oil which comprises subjecting said olefin hydrocarbons in liquid phase to the action of a polymerizing catalyst whereby said olens are converted into heavier hydrocarbon polymers, separating unreacted gaseous hydrocarbons from said polymers, fractionating said polymers in a fractionating zone, and producing said desired distillate lubricating oil and a substantially nonvolatile residue, subjecting said residue to pyrolytic decomposition regulated to regenerate olenic hydrocarbons and to produce lubricating oils of' intermediate viscosity boiling within the range of said desired distillate lubricating oil, recycling the products of said decomposition to said fractionating zone and modifying the polymerization of said olefinic hydrocarbons by recycling at least a portion of the products of said decomcating oil and a high knock rating gasoline,

which comprises polymerizing said olefinic' hydrocarbons in liquid phase in the presence of an active metal halide catalyst whereby polymerization products of a wide range of molecular weight are produced, separating said polymerization products from unreacted gases, frac'tionating said polymerization products in a fractionating zone into gasoline, cycle oil, Diesel lubricating oil, and a residual oil fraction, depolymerizing said residual oil fraction to produce unsaturated products capable of further polymerization, introducing said depolymerization products into said fractionating zone at a point below the point of withdrawing said Diesel lubricating oil fracl tion. and recycling unsaturated depolymerization products from said fractionating zone to said catalytic polymerization step frstmentioned, thereby modifying the polymerization of said olenic hydrocarbons.

5. The process of claim 4 wherein said lastmentioned depolymerization products are normally gaseous hydrocarbons. i

6. The process of converting normally gaseous olen hydrocarbons substantially entirely into a desired distillate lubricating oil and high knockrating gasoline by the processof polymerization, which comprises subjecting said olens in a. liquid phase to the action of a polymerizing catalyst at a. temperature between 0 and 100 F.,

separating unreacted paraffinic gases from the polymerization products, fractionating the polymerization products in a fractionating zone and withdrawing therefrom said desired gasoline fractions and distillate lubricating oil fraction, subjecting the remaining fractions of said polymerization products to thermal depolymerization, thereby producing additional amounts of normally gaseous olens, gasoline and desired distillate lubricating oil, and recycling said depolymerization products to said fractionating zone wherein said gasoline and distillate lubricating oil resulting from depolymerization vare fractionated and combined with the gasoline and distillate lubricating oils produced by said catalytic polymerization reaction.

7. The process of converting a mixture of butane and butylene hydrocarbons into high viscosity ,index distillate lubricating oil 'and high knock rating motor fuel which comprises polymerizing said butylenes into a wide range of polymers by treating said hydrocarbon mixture with a polymerizing catalyst, removing unreacted butane and butylenes, fractionating said polymers in a fractionating zone into a gasoline fraction, a distillate lubricating oil fraction and a heavy residual oil fraction, subjecting said heavy residual oil fraction to decomposition whereby butylenes are formed, recycling the products of said decomposition to the said fractionating zone, and recycling reformed butylenes from said fractionating zone to said polymerization operation where they are lconverted into additional amounts of said desired high viscosity index distillate lubricating oil,

EMMET R. KIRN. NATHAN FRAGEN, 

